Cracks often develop in pavement roadways. Such roadways are constructed of different types of surfaces such as bituminous concrete, asphalt binders, asphalt emulsions and cement concrete. Cracks result from a variety of conditions such as, inter alia, poor quality base materials, lack of or inadequate compaction, surface movement, oxidation, overloading, and water penetration. Some cracks result from expansion and contraction due to weather conditions including climatic temperature changes. The widest and deepest cracks often appear at the longitudinal paving seams in bituminous concrete, typically caused by cold rolling. Some other types of cracks are intentionally made. For example, utility excavations involve cuts into roadways. These cracks are located at the perimeter of the excavation itself. Other small apertures, e.g., small potholes and pavement delaminations may also be fixed using crack repair methods. With scheduled crack repairs and maintenance, pavement surface life can be greatly extended, postponing the need for repaving the entire roadway surface.
Crack and aperture repairs may be needed urgently for safety reasons or where traffic conditions make lengthy road closures inconvenient or in some cases unacceptable. These repairs are ideally made as quickly, and as economically, as possible.
There are various methods of making repairs of such cracks. Hot crack "sealing" is the most common method in which the crack is first cleaned by a mechanical device or by the application of compressed air. The crack is then filled with a hot sealing substance and blotted with a cover material. The next step in the process is to allow the site to cure. This process is usually performed in temperatures well above freezing.
Preparation of the hot sealing substance requires various mixing steps at elevated temperatures and continued agitation of sealing materials which must be placed in heated oil in double-jacketed kettles. This process is costly due to the specialized equipment needed, and the substantial labor requirements involved. The asphalt-based and additive enhanced materials are also comparatively expensive.
More recently, cold processes have been developed which can be performed in colder temperature conditions and do not require the specialized equipment needed for hot crack sealing. However, problems have arisen with such processes especially in connection with dust clouds forming during the repair process. More specifically, known cold processes include filling the crack or aperture with a petroleum emulsion until voids no longer exist. The petroleum emulsion is then covered with a layer of a mineral filler. The mineral filler typically consists of sand, stone dust, stone-sand, limestone, rock "screenings", washed screenings and the like.
In this process, the repairer fills the site with petroleum emulsion and then applies the mineral filler on the surrounding surface as a coating layer. However, the mineral filler produces a great deal of airborne dust. A dust cloud can be formed by traffic in the lane and, it is then aggravated by the passage of traffic in other lanes. This can produce extremely low visibility conditions that may lead to road closure.
In addition to the dust problems, there are other problems associated with cold processes. More specifically, the mineral filler can be quite expensive. It is also rather heavy causing labor requirements to be substantial. Moreover, the accumulation of the mounded mineral filler combined with the petroleum emulsion can leave a ripple effect on the roadway surface, creating a rough surface for vehicular traffic.
One advantage to using the cold process relates to roadway rejuvenation. Specifically, roadways are constructed and repaired with the additional goal of longer road surface life. Sometimes a roadway can be later rejuvenated when repair material is subsequently spread out by tires of passing vehicles. The materials fill in hairline cracks which may be beginning to form in the roadway. This usually occurs, if at all, after the winter when temperatures begin to warm and a repaired crack site becomes somewhat tacky. The tires of passing vehicles pick up materials and spread them to other areas of the pavement. However, whether this occurs with known cold processes can be unpredictable.
There remains a need for a method of repairing cracks in roadways which does not produce dangerous airborne dust and does not result in large amounts of road closure time. There remains a further need for a process that is less costly in that it utilizes materials that are comparatively less costly than prior known materials and such materials, being lighter, involve fewer labor requirements than known prior methods. Another need exists for a process which results in a smooth surface with little ripple effect. There remains a further need for a method which increases the likelihood of roadway rejuvenation when materials are subsequently spread by passing vehicles.